1. Field of the Invention
This invention relates generally to a device useful in the analysis and treatment of structural or positional abnormalities in the foot and lower leg, and more specifically, this invention relates to a device for quickly and easily providing measurements of the varus and valgus of the rearfoot and forefoot, as well as the dorsiflexion and plantarflexion of the foot about the ankle axis.
2. Description of the Prior Art
Problems of the foot and lower leg can frequently be corrected, or at least compensated for or controlled, by the utilization of an appropriate device (such as a shoe insert or orthotic device). In more extreme cases, surgical correction may be required. In either circumstance, an appropriate biomechanical evaluation of the foot and lower leg is required.
The foot, ankle and lower leg are, like many other areas of the body, extremely complex in terms of the various interrelationships that affect the comfort, mobility and function of a person. However, there are certain interrelationships that have a significant overall effect and which can be determined in a quantitative sense. Three of these that are particularly pertinent to the foot and lower leg are forefoot deformity (varus or valgus), rearfoot deformity (varus or valgus) and the dorsiflexion and plantarflexion of the foot about the ankle. Varus and valgus are technical terms that signify, inter alia, a twisting or torsion of the forefoot or rearfoot in a desired plane. Varus (or inversion of the foot) is a position wherein the lateral side (outside) of the foot is on the ground, while the medial side (inside) is raised above the ground. Similarly, valgus (or eversion of the foot) is a position wherein the medial side of the foot is on the ground while the lateral side is raised above the ground. These positions can occur independently in the forefoot and in the rearfoot. Dorsiflexion is the position wherein the foot is flexed upwardly toward the shin or lower leg. Conversely, plantarflexion is the position wherein the foot is extended downward away from the shin or lower leg.
Measurement of these critical characteristics in the past has been very imprecise and subjective, while being often impossible to duplicate. Basically, the prior art procedure is to "eyeball" or visually determine a vertical bisection of the heel or calcaneus bone by palpation or feel of this bone. This vertical bisection would then be drawn on the skin of the patient and used as a reference for attempting to visually estimate the angular deviation of the forefoot and rearfoot.
While to the present day measurement of the rearfoot deformity is based upon a visual comparison of an "eyeballed" vertical bisection of the calcaneus and an "eyeballed" vertical bisection of the lower leg, there at least has been a minor advance in the measurement of forefoot deformity. Thus, at least one prior art device utilizes a pivoted plate under the ball of the foot to give an indication of the plane of the ball of the foot, but even this device still relies upon a comparison of a mechanically derived perpendicular to the plane of the ball of the foot with an "eyeballed" vertical bisection of the calcaneus or heel.
Obviously, the prior art leaves much to be desired in terms of providing reliable and accurate information upon which a biomechanical or orthopedic evaluation of the foot and lower leg can be based.